Abstract: An EUV radiation source that employs a low energy laser pre-pulse and a high energy laser main pulse. The pre-pulse generates a weak plasma in the target area that improves laser absorption of the main laser pulse to improve EUV radiation emissions. High energy ion flux is reduced by collisions in the localized target vapor cloud generated by the pre-pulse. Also, the low energy pre-pulse arrives at the target area 20–200 ns before the main pulse for maximum output intensity. The timing between the pre-pulse and the main pulse can be reduced below 160 ns to provide a lower intensity of the EUV radiation. In one embodiment, the pre-pulse is split from the main pulse by a suitable beam splitter having the proper beam intensity ratio, and the main pulse is delayed to arrive at the target area after the pre-pulse.

Abstract: An EUV radiation source (40) that includes a nozzle (42) positioned a far enough distance away from a target region (50) so that EUV radiation (56) generated at the target region (50) by a laser beam (54) impinging a target stream (46) emitted from the nozzle (42) is not significantly absorbed by target vapor proximate the nozzle (42). Also, the EUV radiation (56) does not significantly erode the nozzle (42) and contaminate source optics (34). In one embodiment, the nozzle (42) is more than 10 cm away from the target region (50).

Abstract: A laser-plasma EUV radiation source (10) that employs one or more approaches for preventing vaporization of material from a nozzle assembly (40) of the source (10) by electrical discharge from the plasma (30). The first approach includes employing an electrically isolating nozzle end, such as a glass capillary tube (46). The tube (46) extends beyond all of the conductive surfaces of the nozzle assembly (40) by a suitable distance so that the pressure around the closest conducting portion of the nozzle assembly (40) is low enough not to support arcing. A second approach includes providing electrical isolation of the conductive portions of the source (40) from the vacuum chamber wall. A third approach includes applying a bias potential (52) to the nozzle assembly (40) to raise the potential of the nozzle assembly (40) to the potential of the arc.

Abstract: An EUV radiation source (40) that includes a nozzle (42) positioned a far enough distance away from a target region (50) so that EUV radiation (56) generated at the target region (50) by a laser beam (54) impinging a target stream (46) emitted from the nozzle (42) is not significantly absorbed by target vapor proximate the nozzle (42). Also, the EUV radiation (56) does not significantly erode the nozzle (42) and contaminate source optics (34). In one embodiment, the nozzle (42) is more than 10 cm away from the target region (50).

Abstract: An EUV radiation source that employs a low energy laser pre-pulse and a high energy laser main pulse. The pre-pulse generates a weak plasma in the target area that improves laser absorption of the main laser pulse to improve EUV radiation emissions. High energy ion flux is reduced by collisions in the localized target vapor cloud generated by the pre-pulse. Also, the low energy pre-pulse arrives at the target area 20-200 ns before the main pulse for maximum output intensity. The timing between the pre-pulse and the main pulse can be reduced below 160 ns to provide a lower intensity of the EUV radiation. In one embodiment, the pre-pulse is split from the main pulse by a suitable beam splitter having the proper beam intensity ratio, and the main pulse is delayed to arrive at the target area after the pre-pulse.

Abstract: An EUV radiation source that creates a stable solid filament target. The source includes a nozzle assembly having a condenser chamber for cryogenically cooling a gaseous target material into a liquid state. The liquid target material is filtered by a filter and sent to a holding chamber under pressure. The holding chamber allows entrained gas bubbles in the target material to be condensed into liquid prior to the filament target being emitted from the nozzle assembly. The target material is forced through a nozzle outlet tube to be emitted from the nozzle assembly as a liquid target stream. A thermal shield is provided around the outlet tube to maintain the liquid target material in the cryogenic state. The liquid target stream freezes and is vaporized by a laser beam from a laser source to generate the EUV radiation.

Abstract: A laser-plasma EUV radiation source (10) that employs one or more approaches for preventing vaporization of material from a nozzle assembly (40) of the source (10) by electrical discharge from the plasma (30). The first approach includes employing an electrically isolating nozzle end, such as a glass capillary tube (46). The tube (46) extends beyond all of the conductive surfaces of the nozzle assembly (40) by a suitable distance so that the pressure around the closest conducting portion of the nozzle assembly (40) is low enough not to support arcing. A second approach includes providing electrical isolation of the conductive portions of the source (40) from the vacuum chamber wall. A third approach includes applying a bias potential (52) to the nozzle assembly (40) to raise the potential of the nozzle assembly (40) to the potential of the arc.

Abstract: An EUV radiation source that creates a stable solid filament target. The source includes a nozzle assembly having a condenser chamber for cryogenically cooling a gaseous target material into a liquid state. The liquid target material is filtered by a filter and sent to a holding chamber under pressure. The holding chamber allows entrained gas bubbles in the target material to be condensed into liquid prior to the filament target being emitted from the nozzle assembly. The target material is forced through a nozzle outlet tube to be emitted from the nozzle assembly as a liquid target stream. A thermal shield is provided around the outlet tube to maintain the liquid target material in the cryogenic state. The liquid target stream freezes and is vaporized by a laser beam from a laser source to generate the EUV radiation.